Field of the Invention
The present invention relates to a method for performing a measurement report of a terminal in a mobile communication system and a terminal for the same.
Related Art
The International Telecommunication Union Radio communication sector (ITU-R) performs a standardization work of International Mobile Telecommunication (IMT)-Advanced which is a next-generation mobile communication system after 3rd generation.
3rd Generation Partnership Project (3GPP) as a system standard that meets requirements of the IMT-Advanced prepares for LTE-Advanced (hereinafter, referred to as LTE-A) acquired by enhancing long term evolution (LTE) based on Orthogonal Frequency Division Multiple Access (OFDMA)/Single Carrier-Frequency Division Multiple Access (SC-FDMA). The LTE-A is one of dominant candidates for the IMT-Advanced.
Candidate technologies to be used in the LTE-A include carrier aggregation (CA). The carrier aggregation is a technology that aggregates a plurality of component carriers (CCs) having a narrow band to configure a wideband. The component carriers include a downlink component carrier and an uplink component carrier. A cell may be defined as a pair of the downlink component carrier and the uplink component carrier or the downlink component carrier and in this case, the carrier aggregation may be appreciated as aggregation of a plurality of cells.
In the carrier aggregation, a primary cell in which a terminal establishes an initial connection process/reconnection process with a base station and a secondary cell added in addition to the primary cell are provided.
Meanwhile, in a mobile communication system, supporting mobility of the terminal is required. To this end, the terminal continuously measures a quality for a serving cell providing a current service and a quality for a neighboring cell. The terminal reports a measurement result to a network at an appropriate time and the network provides optimal mobility to the terminal through handover, and the like.
The terminal may report the measurement result by a method triggered by an event. That is, when a specific event occurs, the terminal reports the measurement result. In this case, a target cell of each event is predetermined. For example, among events, events are for the serving cell, the neighboring cell, the primary cell, and the secondary cell, respectively or events are for combinations of the cells are provided. The secondary cell is basically treated as the serving cell, but may be treated as the neighboring cell in the specific event.
When the neighboring cell satisfies the specific event, the terminal makes the neighboring cell be included in ‘cellsTriggeredList’. A current standard prescribes that the neighboring cell is included in ‘measResultNeighCells’ to be transmitted if the ‘cellsTriggeredList’ is not empty and the neighboring cell is not included in the ‘measResultNeighCells’ but excluded if the ‘cellsTriggeredList’ is empty.
The base station may add the neighboring cell to the terminal as the secondary cell by using a measurement report including the ‘measResultNeighCells’. In this case, the neighboring cell needs to be basically treated as a serving cell.
However, the current standard does not prescribe modification of the ‘cellsTriggeredList’ when the neighboring cell is added as the secondary cell. Therefore, the neighboring cell continuously remains in the ‘cellsTriggeredList’, and as a result, the neighboring cell is included in the ‘measResultNeighCells’ to be transmitted.
This causes unnecessary measurement report transmission of the terminal to bring about battery consumption. Further, when the base station performs resource management based on the ‘measResultNeighCells’, ambiguity may occur.